The present invention is related to a system (and method) for RF communication between a host, such as a host computer system or terminal, and a portable printer, and relates particularly to, a system for RF communication between a host and a portable printer by linking the printer to the host to provide RF communication there between, such that the printer operates responsive to the linked host. The present invention is suitable for use in environments where multiple portable printers and host devices are present to enable different hosts and printers to be linked for communication with each other, where each printer operates to print information received from a linked host on media contained in the printer.
Miniature portable printers have been used on factory floors, in warehouses, and in retail establishments for ticket printing and inventory control. For example, such portable label printers are described in U.S. Pat. Nos. 5,806,993, and 5,267,800. These printers print indicia, such as text or bar codes, on media, such as adhesive-back label stock or paper, from a roll in the printer housing. Being miniature, such portable printer are more useful than heavier stationary or briefcase printers, as they are of a small weight and size to be easily can be carried or worn by a user. Each of the printers can interactively communicate with a host terminal or computer system. To change communication with different host terminals or computers (host devices), the user must establish communication with the new host device which often requires the user to manually reset the printer and host via the printer keypad, or to reconnect cabling between the new host device and the printer. This can be time consuming and tedious for the user, and can be difficult when the communication protocol of the host device and the printer are dissimilar. Accordingly, it is desirable to easily link a miniature, portable printer to different ones of host devices, and once linked, can to communicate therewith. This would be especially useful in a retail environment having multiple host devices and portable printers.
It is the principal object of the present invention to provide an improved system for communication between a host device and a portable printer in which the host and printer can be linked to each other to enable data communication there between by RF signals.
It is another object of the present invention to provide an improved system for data communication by RF signals between a host device and a portable printer in which the host device has either, or both, an optical scanner or RFID tag reader to identify an identifier (such as a serial number) associated with the address of the printer in one of a scanned barcode on the printer housing, a read RFID tag coupled to the printer, or an RF broadcast received from the printer, such that the host can address the printer for linking to the host by the address associated with the scanned, read, or received printer identifier.
It is still another object of the present invention to provide an improved system of data communication by RF signals between a host device and a portable printer in which either one or both the host device and the printer can identify a clear RF communication channel before sending an RF signal transmission.
Yet another object of the present invention is provided an improved system for data communication by RF signals between a host device and a portable printer in which the host device and portable printer are capable of negotiation communication characteristics, such as baud rate and encoding format.
Briefly described, the system includes at least one host terminal or computer system (referred to herein as host or host device) and at least one portable printer. The host device has an RF communication interface and a programmed controller to send and receive data via the interface to the printer. The portable printer has a printing mechanism for printing on media contained in the printer, an RF communication interface, and a programmed controller for controlling the printing mechanism and the RF communication interface responsive to data received from the host. Each portable printer has a unique identifier, such as a serial number, which is recorded in a barcode present on the housing of the printer, and/or in an RFID tag coupled to the printer. The host has either, or both, an optical scanner or an RFID reader to read the printer""s barcode, or RF signals from the RFID tag, to obtain the printer""s identifier. Utilizing this identifier, the host identifies the unique address of the printer to be linked to the host via an association between printer identifiers and addresses. The host and printer are linked for data communication by the host sending a wakeup packet addressed to the printer, the printer sending to the host a ready packet, the host sends a force link packet identifying the host""s unique address to the printer, and the printer then sending to the host an accept link packet indicating that the printer is linked to the host for subsequent data communication there between, in which the printer responds to data received from the host having the host""s address.
Other host devices can similarly be linked to the printer, such that when each of the hosts are linked to the printer, the printer is responsive to the linked host. The host and printer may negotiate data communication characteristics, such as baud rate and encoding format, using the wakeup packet and a ready packet during at the start of the data transfer process to enable communication at the highest baud rate and with proper encoding/decoding of data. Before a packet is sent in a RF transmission to either the printer or host, either, or both the printer and host finds a clear channel for such transmission and receipt of a reply to the transmission, and retries the transmission when no reply is received. The system may be used with multiple hosts and portable printers, such that different hosts can be linked to different printers.
In the system, the host device initiates the link to the portable printer, such as described above. However, the printer may also initiate linking with a host device by broadcasting an RF signal with the printer""s identifier (or address) in a link request packet. The first host in proximity to the printer, which responds to the link request packet with a successful link procedure, as described above, is then linked to the printer. This embodiment enables a host, which may not have an optical barcode scanning and/or RFID tag reading capability, to be linked to a printer.